One OpenVPN server and two clients with certificates

[Igor]

I've been fighting with a router for 6 hours. I can't connect a second client to OpenVPN.

Installed OpenVPN server on the router. I see "Data ciphers: CHACHA20-POLY1305:AES-128-GCM:AES-256-GCM:AES-128-CBC:AES-256-CBC".
The client on another router connects only with a certificate. Everything is working.

I install the third router as an OpenVPN client. The client does not connect because no "Client Certificate" and "Client Key".

<cert>
   paste client certificate data here
</cert>
<key>
   paste client key data here
</key>

How to generate them correctly?

Format JFFS partition at next boot = Yes
Enable JFFS custom scripts and configs = Yes

Did not help.

Generating OpenVPN keys using Easy RSA

Third party firmware for Asus routers (newer codebase) - RMerl/asuswrt-merlin.ng

github.com

I generated the client keys (CN=client) and inserted them into the GUI. There are no errors in the log Error: "VERIFY ERROR: depth=0, error=unable to get local issuer certificate", but there is no connection either - it constantly tries to reconnect. Did not help.
If I insert certificates from the first router, then the VPN is installed, but two clones appear on the server, it connects them randomly.

Maybe I've already made a mistake... Maybe there is an instruction? I can reset the router to factory settings. Please.